The present invention relates to a new and improved method of using a controlled or controllable magnetic bearing arrangement in a textile winding device. The present invention also relates to a new and improved construction of a winding device for use with a spinning machine and equipped with such controlled or controllable magnetic bearing arrangement.
In its more particular aspects the present invention specifically relates to a new and improved method of using a controlled magnetic bearing arrangement which is intended for use with a rotatable shaft in a textile winding device. The controlled magnetic bearing arrangement contains a predetermined number of stationary electromagnets arranged in a substantially circular annular relationship. An electronic control means or circuit is provided for appropriately controlling the electric currents flowing through the stationary electromagnets.
A controlled magnetic bearing arrangement as described, for example, in a brochure published by Societe de Mechanique Magnetique, BP 431,27204 Vernon Cedex, France and commercialized under the trademark "ACTIDYNE", can be utilized for supporting shafts which rotate at variable rotational speeds. The shaft is floatingly supported and can pass through critical rotational speeds without the excitation or generation of dangerous resonance vibrations.
Known winding devices for use during spinning operations contain a plurality of packages which are located on a common support shaft and which are simultaneously wound. When the packages reach their fully-wound condition, the weight of each individual package may amount to more than 20 kg. It is desirable during the winding operation to select the winding speed in such a manner that the related threads are wound up on each package at a rate of up to 6,000 meters per minute.
These requirements cannot be satisfied by the currently available means or expedients or can be satisfied only inadequately. The encountered difficulties include bending of the package supporting or support shaft in dependence upon the weight of the packages, and more particularly the presence of critical rotational speeds, that is to say, rotational speeds associated with different orders of the resonance vibrations of the package support shaft. These critical rotational speeds are caused by the occurrence of resonance at the natural vibrational frequencies of the package support shaft. The package support shaft can be destroyed at such critical rotational speeds and this can be extremely dangerous considering the high rotational speeds and the weights of the processed packages.
Attempts have been made to adapt the currently used winding devices to the spinning machines by immediately winding up the thread or the like which is delivered by the spinning machine, and adapting the rotational speed of the package to the thread delivery speed, see, for example, U.S. Pat. No. 4,394,985, granted July 26, 1983. This requires a continuous adaptation to the continually increasing weights of the packages and to the continually decreasing rotational speed during the winding operations. During such adaptation, operation at or near the critical rotational speeds can arise of necessity. Due to the previously mentioned considerable danger, operation in the region of the critical rotational speeds during such adaptation cannot be tolerated. Thus, optimal rotational speeds cannot be maintained under certain conditions which necessarily arise during the previously mentioned continuous variations, and thus the spinning machine or installation cannot be operated or used at full capacity.